There is a critical need to define the molecular signaling pathways that are the crucial regulators of thrombin- mediated podocyte injury without which, the development of targeted, safe and effective therapies for nephrotic syndrome is likely to remain limited. The overall objective of this proposal is to develop the career of a hemostasis physician-scientist who will learn to apply coagulation biology, molecular biology, molecular pharmacology, and systems biology techniques to define the molecular mechanisms of thrombin-mediated glomerular injury. The central hypothesis is that, during proteinuria, podocytes are exposed to thrombin which exacerbates podocyte injury via activation of protease activated receptors (PAR). Using established podocyte cell culture lines, the PAR species that are essential for thrombin-mediated apoptosis induction will be determined through anti-PAR antibody blockade, shRNA knock-down, and proximity ligation experiments. Supplementation with antithrombin, a non-specific thrombin inhibitor, is known to attenuate proteinuria in experimental nephrosis models. Thus, the mechanism of action by which antithrombin modifies proteinuria will be determined by pharmacologically manipulating the thrombin signaling axis at each molecular level and examining the impact of each condition on glomerular injury as measured by proteinuria. Using rat and human cultured podocytes, gene expression profiles and transcriptional networks will be evaluated to determine podocyte-specific transcriptional responses to thrombin exposure. Subsequently, these profiles and networks will be correlated with those of isolated rat glomeruli and existing gene expression profiles of glomeruli isolated from human NS renal biopsies to determine thrombin-dependent podocyte transcriptional responses that are relevant to human nephrotic syndrome and simultaneously inform the selection of appropriate preclinical models of these processes. A prioritized strategy will be employed to guide further investigation of high-value candidate genes and their biological pathways. This career development award is directly responsive to the mission of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) which is to support medical research and research training on kidney, urologic, and hematologic diseases. Completion of the training program and research in this career development award is expected generate compelling preliminary data for the awardee to successfully compete for R01 funding to systematically analyze coagulation signaling in glomerular diseases.